Developing a framework taking into account negative environmental impacts to evaluate water-energy-food coupling efficiency

Increased water, energy, and food demand lead to resource risks and environmental threats. There is a complex nexus between the three. Evaluating WEF coupling efficiency based on WEF Nexus helps suggest sustainable resource utilization by analyzing the current resource coupling utilization situation. However, neglecting the influence of the external environment and lacking a clear understanding of the interactions within the WEF system can lead to biased assessments. Therefore, this study considers negative environmental impacts and clarifies interactions within the WEF system based on resource conversion relationships to develop a new framework for evaluating the WEF coupling efficiency. The framework is applied to the Yellow River Basin to provide relevant suggestions for promoting the healthy development of resources and the environment. The results indicate that WEF coupling efficiency in the Yellow River Basin during 2000–2020 was maintained at a medium level with an overall increasing trend. The middle and lower regions are medium to high efficiency, and 65% are on an upward trend. However, the low-efficiency areas are all located upstream, and 80% of them are decreasing. There is a growing gap in WEF coupling efficiency between regions. The increase in efficiency was mainly attributed to improvements in energy and food systems. The water system was the key reason for the lower efficiency. Evaluating environmental impacts based on sensitivity analysis, the energy system's negative environmental factors (NEFs) led to the most significant decrease in WEF coupling efficiency, with an average reduction of up to 8%. Based on the Tobit model to analyze the external drivers of WEF coupling efficiency, WEF coupling efficiency is higher in the case of richer cultivated land resources, more intensive labor force, and less precipitation. In conclusion, promoting technological innovation of the water system, optimizing resource allocation, and controlling pollutant emissions are effective measures to optimize the efficiency of WEF coupling for the high-quality development of the Yellow River Basin.